Moulton first came to prominence in 2014 when he unseated long-term incumbent Rep. John Tierney in a Democratic primary and went on to represent the state's 6th Congressional District, a swath of communities north of Boston including Salem, home of the infamous colonial-era witch trials.

Speculation about a possible Moulton run has been simmering as far back as 2017 when he spoke at a Democratic political rally in Iowa, home of the first-the-the-nation presidential caucuses. At the time he brushed aside talk of a presidential run.

Talk of possible run ramped up during last year's election when the former U.S. Marine helped lead an effort to get other Democratic military veterans to run for Congress — a cause he continues to push.

"16 years ago today, leaders in Washington sent me and my friends to fight in a war based on lies. It's still going on today," Moulton said in a recent tweet. "It's time for the generation that fought in Iraq to take over for the generation that sent us there."

The 40-year-old Moulton also gained national attention for helping lead an effort within the party to reject Nancy Pelosi as House speaker after Democrats regained control of the chamber. Moulton said it was time for new leadership.

Moulton has also been a frequent critic of President Donald Trump — from foreign policy, including Trump's recent veto of a resolution to end U.S. military assistance in Saudi Arabia's war in Yemen, to his push for a wall at the southern border.

And when Trump claimed to be the target of the "single greatest witch hunt of a politician in American history," Moulton responded that "as the Representative of Salem, MA, I can confirm that this is false."

Despite occasionally differing with some on the most liberal wing of the party, Moulton has staked out familiar policy positions for those seeking the Democratic presidential nomination.

He's called health care "a right every American must be guaranteed," pushed to toughen gun laws, was a co-sponsor of the Green New Deal, has championed a federal "Green Corps" modeled after the Civilian Conservation Corps of the 1930s, and has called for an end to the Electoral College.

Money could prove a challenge to Moulton, who has raised $255,000 so far this year and had about $723,000 in his campaign account as of the end of March.

Moulton is now the third political figure from Massachusetts to take a stab at a White House run. U.S. Sen. Elizabeth Warren — a Democrat — and former Massachusetts Gov. William Weld — a Republican — are also running.